This commit restructures noVNC, splitting it into the core directory
and the app directory, with the former containing core noVNC parts,
and the latter containing parts specific to the application.
When `utils/launch.sh` clones websockify, it can be cloned
into the incorrect directory, depending on how `utils/launch.sh`
is run. This commit ensures that websockify is always cloned into
`utils/websockify`.